1. Field of the Invention
The present invention relates to a protection circuit, and more particularly, to a protection circuit for preventing an over-current from an output stage.
2. Description of the Prior Art
Advances in semiconductor technology have resulted in smaller electronic devices. Therefore, the ability of a device to resist heat and other factors which may damage the device is important. An output stage in an audio system should be able to load a large power. In some situations, however, an output terminal of the output stage will inevitably short to ground or to the supply voltage, causing an over current to be generated. If this over current passes through the output stage, it will generate a lot of heat which might cause irreparable damage to the small size output stage. In the prior art, diodes are used as a voltage clamping device for the output stage to pull down the current to a fixed value. However, the fixed current limit value is larger than the normal operating current value. As such, the output stage may be damaged because large limited current sustains in the output stage if the short condition is kept.